An electronic device for an apparatus used outdoors, a typical example being a vehicle such as an automobile or an automatic two-wheeler, uses a card member, an electronic circuit apparatus, or the like having card edge terminals in which a circuit board is sealed by a resin or the like and integrated in order to be watertight. Japanese Patent Publication No. 4478007 discloses an invention of an electronic circuit device covered by a resin-molded portion. The electronic circuit device disclosed in Japanese Patent Publication No. 4478007 has: a circuit board including electronic components thereon; a resin-molded portion made from a resin disposed so as to cover the electronic components; a convex connector having connecting metal terminals and exposed by the resin-molded portion; and a sealing member wound around the outer periphery of the resin-molded portion. Thus, according to the electronic circuit device disclosed in Japanese Patent Publication No. 4478007, it is possible to provide an electronic circuit device which can be reduced in size and cost and which is reliable.
The resin-molded portion formed on such an electronic circuit device is manufactured by mold-forming using two molds in a common manufacturing process. For example, in the method for manufacturing an electronic circuit device disclosed in Japanese Patent Publication No. 4478007, a circuit board is prepared having a convex connector at the end and electronic components mounted on the surface, two molds are prepared having convex sections around the entire inner peripheries so as to form a cavity composed of a first portion corresponding to the outer shape of the resin-molded portion and a second portion containing the convex connector, the circuit board is placed between the two molds, a resin is injected into the cavity through a resin injection inlet formed between the two molds, and the sealing member, which has two or more elevated parts and one or more depressed part as a cross-sectional shape, is placed in a groove formed in the outer periphery of the resin-molded portion manufactured from the molds.
Devices such as the electronic circuit device disclosed in Japanese Patent Publication No. 4478007 are used while connected to an opposing connector. However, with a device such as an electronic circuit device installed in machinery used primarily outdoors, such as an automobile, an automatic two-wheeler, or another vehicle, or agricultural tools, ships, and airplanes; when the portion connected with the opposing connector is exposed to a liquid such as rainwater, infiltration of the liquid into the electronic circuit device or the like must be suppressed. Therefore, a high degree of watertightness is needed between the card member and the opposing connector connected thereto.
However, when the device is manufactured between two molds, as is the case with the method for manufacturing an electronic circuit device disclosed in Japanese Patent Publication No. 4478007, the injected resin material enters through the joining portion of the two molds, and a small protruding burr (parting line) is formed. When a watertight sealing member is mounted on the portion where this burr is formed, or when the portion with the burr is fitted with the sealing member mounted on the opposing connector, the sealing member is raised up by the burr and a small gap is formed. When a small gap is formed, liquid adhering to the connector could infiltrate the connector through capillarity, and there is a risk of problems occurring with the electronic equipment, causing malfunctions and breakdowns.
The burr could also be removed by polishing after the mold-formation, but manufacturing becomes more time-consuming and costly because a polishing step is needed, and there is a risk of problems with product quality in that the size and shape is different than what was designed when the equipment is grinded down by polishing. If a groove for accommodating the sealing member is formed, as is the case with the electronic circuit device disclosed in Japanese Patent Publication No. 4478007, because the burr is formed, there is a risk of a gap being created between the sealing member and the burr within the groove. Furthermore, because the size and shape of the burr is not constant, there is a risk that a product of insufficient watertightness will be manufactured, and there is also a risk that reliability will be compromised.
In the step for manufacturing the resin molded section, because the mold-forming is performed with the substrate lying horizontally as shown in FIG. 13, problems with this method are that the substrate occupies a large area of the mold in a plan view, only a small number of products can be manufactured by a single resin injection, production efficiency is low, and manufacturing costs are high.